This invention relates generally to a steering mechanism for an agricultural tractor in which the front axle is laterally shiftable in response to a steering movement of the steerable wheels and, more particularly, to an implement attachment mechanism which is mounted directly to the shiftable front axle to enhance steering operation associated with front mounted implements.
Tractors, whether used in an agricultural setting or in an industrial setting, typically include a fixed axle through which primary driving power is transferred through fixed wheels rotatably mounted on opposing ends of the fixed axle, and a steering axle having pivotally mounted steerable ground engaging wheels rotatably mounted on the opposing ends thereof to support the chassis of the tractor above the ground. Although supplemental driving power is often provided to the steerable ground engaging wheels, a steering mechanism remotely controllable by the operator from the operator's compartment selectively controls the pivotal movement of the steerable wheels relative to the steering axle.
One such steering mechanism incorporates a transversely disposed, horizontally extending hydraulic cylinder supported by the steering axle and connected to the opposing steerable wheels. This hydraulic cylinder affects pivotal movement of the steerable wheels about their respective pivotal connections to the steering axle by manipulating the pressures in the hydraulic cylinder to effect a transverse extension of cylinder rod, causing a turning of the wheels.
Due to physical limitations relating to the range of movement of the steering mechanism and to the eventual interference between the steerable wheels and the steering axle, the amount of pivotal movement of the steerable wheels relative to the steering axle is limited to a given turning angle. This maximum turning angle defines the minimum turning radius of the tractor for a given wheel base length and tread spacing. The selection of the length of the wheel base, i.e., the distance between the fixed axle and the steering axle, is a compromise between the need to minimize the turning radius and, therefore, minimize the wheel base length, and to maximize ride considerations which require longer wheel base lengths.
These conflicting wheel base requirements can be better resolved by a steering mechanism incorporating a laterally shifting front axle that is movable in response to a corresponding steering movement of the steerable wheels, which will decrease the turning radius of the tractor for any given wheel base length.
Traditionally, front mounted implements are connected to a three-point hitch attachment mechanism supported from the frame of the chassis to provide adequate support therefor. Steering of the tractor when front mounted implements are utilized can be difficult, particularly when the implement is a tillage device actively engaged with the ground. Such steering difficulties counteract the steering capability enhancements associated with a compound steering mechanism.
It would, therefore, be desirable to provide a mechanism for mounting an implement attachment mechanism directly to the laterally shiftable front axle so that the implement connected thereto would be laterally shiftable with the steering movement of the compound steering mechanism.